Field of the Invention
The present invention relates to a system for detecting seizures, such as tonic-clonic seizures, comprising:                at least one processor unit capable of recording an electromyographic signal from a sensor unit,        one or more analysis modules configured to analyze the recorded signal, and        one or more evaluation modules configured to evaluate the output signals from the analysis modules.        
The present invention further relates to a method of analyzing the dynamics of a seizure, such as tonic-clonic seizures, comprising the steps:                recording an electromyographic signal from a sensor unit,        analyzing the recorded signal using one or more analysis modules, and        evaluating the output signal using one or more evaluation modules.        
Description of Related Art
It is well known to analyze abnormal biomedical events, such as seizures, in order to determine the characteriztics of the seizure which may then be used to detect or identify another seizure or other similar seizures. This method is particular relevant when detecting or predicting the onset of seizures.
Today, people suffering from seizures occurring from abnormal neuronal activities, such as epileptic seizures, need to be admitted to special clinics or hospitals where the medical staffs, such as primary caregivers, doctors or neurologists, are able to analyze, manage and classify the seizures. Once admitted, seizures are often detected and recorded by using multiple signal processing means, e.g., video-EEG, CT- and MRI-scanning, EEG and CT/MRI-scanning, motion detection or other signal processing means. This process is not only very time consuming, but also requires a lot of data analysis either automatically or manually in order to determine the characteriztics of the seizure.
Generalized tonic-clonic seizures (also called GTCS or GTC seizures) are the most common afebrile seizure type in the general population and also the most dramatic of all seizures. However, the underlying pathophysiologic mechanisms (dynamics) are not yet fully elucidated since it is obscured by artifacts. Most of the data come from in-vitro studies or animal models (see, Zifkin, B. G., Dravet, C. (2008) Generalized tonic-clonic seizures. In J. Engel, Jr, T. A. Pedley (Eds) Epilepsy. A comprehensive textbook. 2nd ed., Lippincott, Williams a Wilkins, Philadelphia, vol 1, pp. 553-562). The in-vivo human data on the electrophysiology of the GTCS are mainly based on EEG recordings in the 1950ies from patients who were curarized (to avoid artifacts) and had GTCS induced by administration of pro-convulsive drugs such as pentetrazol or bemegride (see, Ajmone-Marsan, C. and Ralston, B. L. The Epileptic Seizure. Its Functional Morphology and Diagnostic Significance, Charles C Thomas, Springfield, Ill.; 1957 (pp. 65-72), and Gastaut, H. and Broughton, R. Clinical and electroencephalographic features, diagnosis and treatment, Epileptic Seizures. Charles C. Thomas, Springfield, Ill.; 1972 (pp. 26-47)).
GTC seizures are commonly divided into a tonic phase and a clonic phase and the whole seizure period often lasts no more than a few minutes. Muscles are at the end of the common final neural pathway involved in the GTCS, and surface electromyography (sEMG) signals provide valuable information at a high temporal resolution. A previous study (see Conradsen et al., Patterns of muscle activation during generalized tonic and tonic-clonic epileptic seizures, Epilepsia, Volume 52, Issue 11, 2011) has shown that the quantitative sEMG parameters calculated for the whole seizure period differed significantly among a GTCS, a tonic seizure and a voluntary activation acted by healthy controls.
Today, the start-points and stop-points of the seizure period and of the different phases occurring in the seizure period are often determined manually by the person(s) analyzing the signals. This leads to some uncertainty about the precise start- and stop-point for each phase and the length (period) of the seizure.